Such a power supply system is known from chapter 5.3 of the thesis by Christoph Meyer, entitled “Key Components for Future Offshore DC Grids.” The converter converts a direct current into another direct current, connected in input to a direct current source and delivering a direct current in output on the direct bus. The direct-direct converter includes an inverter connected to the primary of a transformer, and the current is then rectified through a unidirectional diode bridge, the current circulating only from the direct input source to the direct bus connected in output of the converter.
The direct circulation bus of the electrical current is a so-called high-voltage bus, having a voltage with a value higher than 1 kV. The circulation bus makes it possible to connect the current source and the converter arranged in a wind turbine, on the one hand, to a remote electrical grid on the other hand. The circulation bus includes wired electrical connections, which then have a length for example greater than several hundred meters. The converter and the current source are for example arranged offshore, and the electrical grid to which they are connected by means of the circulation bus is arranged onshore.
However, when the current source does not provide energy, for example in the absence of wind in the case of a wind turbine, auxiliary equipment such as sensors, measurement equipment, or surveillance equipment is no longer powered by the current source, and also cannot be powered by the electrical grid due to the single circulation direction of the direct current on the bus, from the source to the network.